Answer

A Data Class in Kotlin is a class whose main purpose is to hold data. The compiler automatically derives standard functionality from the properties declared in the primary constructor.

Key Features

When you mark a class as `data`, Kotlin automatically generates:

1. `equals()` / `hashCode()`: For comparing object content.
2. `toString()`: Prints a readable string like `User(name=John, age=30)`.
3. `copy()`: Creates a copy of the object with some properties modified.
4. `componentN()` functions: Enables destructuring declarations.

Requirements

• The primary constructor must have at least one parameter.
• All primary constructor parameters must be marked as `val` or `var`.
• Data classes cannot be abstract, open, sealed, or inner.

Example

```kotlin data class User(val name: String, val age: Int)

fun main() { const user1 = User("Alice", 25) const user2 = user1.copy(age = 26) // Copy with modification

println(user1) // User(name=Alice, age=25)

// Destructuring
const (name, age) = user1
println("$name is $age years old")

} ```